Materials and Manufacture of Soft and Curvilinear Electronics

Unconventional electronic devices in soft and three-dimensional (3D) curvilinear formats hold promise in a broad range of applications, such as wearable computers, stretchable displays, biomedical instruments, and personal health-care devices, etc. To create such a type of electronic devices, dedicated materials and manufacturing technologies are needed. Although a lot of knowledge in these and related aspects currently exists, the realization of soft and 3D curvilinear electronics still faces many challenges. For instance, no versatile manufacturing technology is available to effectively manufacture 3D curvilinear electronics; the existing strategies for building soft and stretchable electronics associated with complicated structural designs and sophisticated fabrication processes limits their future development and implementation for many applications. To this end, this dissertation aims to provide both fundamental and application studies to address some of the existing material and manufacturing challenges and to validate them through various device evaluation and demonstrations. This dissertation mainly covers four major topics. The first topic introduces a new manufacturing approach, namely conformal additive stamp (CAS) printing, which utilizes a deformable balloon stamp to pick up and print element or components of interest, to fabricate 3D curvilinear electronics. The second topic is to introduce a dedicated example of 3D curvilinear electronics, specifically a multifunctional smart contact lens, by utilizing CAS printing. The demonstrated smart contact lens allows continuous health monitoring including eye intraocular pressure, ocular surface temperature, tear glucose level, etc. The third topic introduces sol-gel-on-polymer processed indium zinc oxide (IZO) semiconductor nanomembrane based ultra-thin stretchable electronics with advantages of multifunctionality, simple manufacturing, imperceptible wearing, and robust interfacing, which is employed as wearable closed-loop HMI system. The fourth topic introduces high performance rubbery electronics based on intrinsically stretchable semiconductor with enhanced carrier mobility. The rubbery electronics retain electrical performance without significant loss under mechanical stretching of 50%. Overall, this dissertation includes a whole set of results in materials, manufacturing technologies, mechanical studies, and devices to illustrate the associated novel aspects in these soft and curvilinear electronics that have been developed or can be developed in the future.